x402 Signer Recovery Verifier

Recovers the ECDSA signer address from a caller-supplied EIP-712 digest and signature in (r,s,v) or (r,s,yParity) form. Normalizes the recovery-id across the raw bit (0/1), legacy Ethereum v (27/28), and EIP-155 v (chainId*2+35/36) conventions, each a well-known transcription trap. Reports the recovered address plus a separate boolean comparison against any caller-claimed from address (never silently failing when no claim is supplied). Signature recovery comes from the already-vendored, pinned noble-curves bundle (@noble/curves secp256k1 Signature.recoverPublicKey); malformed or invalid-recovery-id signatures produce a clean INDETERMINATE/RECOVERY_FAILED finding, never a thrown exception. Proves that an address's private key signed the exact digest supplied; does not prove settlement, spend, that funds moved, or that the authorization was ever submitted on-chain. Zero network calls; never a facilitator, proxy, gateway, or settlement relay.

Tool URL: https://ainumbers.co/chaingraph/art-591-x402-signer-recovery-verifier.html